1. Technical Field
The present invention relates to an ink composition and an image forming method.
2. Related Art
Image recording methods for forming an image on recording media, such as paper, based on image data signals include electrophotographic methods, sublimation transfer methods, melt transfer methods, and inkjet methods.
Since the electrophotographic recording method requires a process of forming an electrostatic latent image on a photoreceptor drum by means of electric charge and light exposure, there arise problems in that a relatively more complicate system is necessary, leading to higher production costs. On the other hand, while the apparatus used for a thermal transfer method is inexpensive, there are problems in that use of ink ribbons causes higher running costs and generates waste materials.
In contrast, in an inkjet recording method, an image is formed directly on a recording medium by ejecting ink only to the desired image portion using an inexpensive apparatus. Thus, the inkjet recording method is an excellent image recording method which enables efficient use of ink, of which running cost thereof is inexpensive, and which generates little noise.
Among the ink compositions used for inkjet recording of an image, an active energy ray-curable aqueous ink may be suitably used for printing of an image, a pre-treatment for imparting printability to a recording medium, a post-treatment for protecting and/or modifying a printed image, or the like. Furthermore, since the active energy ray-curable aqueous ink contains water as the main component, it is highly safe and applicable to a high-density inkjet recording owing to a lower viscosity thereof. Thus, the active energy ray-curable aqueous ink serves as a technique having many excellent characteristics and potential.
Examples of basic constitutional materials of an active energy ray-curable aqueous ink include water, a polymerizable substance, a polymerization initiator that generates a radical in response to a radiation and initiates polymerization, and a colorant (such as a pigment or a dye). Japanese Patent Application Laid-Open (JP-A) No. 2007-119449 discloses examples of aqueous polymerizable substances and aqueous polymerization initiators, and discloses an inkjet recording ink composition with which a film having excellent adhesiveness is obtained by light exposure.